Mechanism of Wharton's Jelly-derived mesenchymal stem cells in promoting peripheral nerve regeneration

Warton’s jelly-derived MSCs (WJ-MSCs) play key roles to improving nerve regeneration in acellular nerve grafts (ANGs), however the mechanism of WJ-MSCs releted nerve regeneration remain unclear. This study investigated how WJ-MSCs contribute to peripheral nerve regeneration by examining immunomodulatory and paracrine effects, and differentiation potential. WJ-MSCs were isolated from umbilical cords. ANGs (control) or WJ-MSC-loaded ANGs (WJ-MSCs group) were transplanted in injury animal model. Functional recovery was evaluated by ankle angle and tetanic force measurements up to 16 weeks post-surgery. Tissue biopsies at 3, 7, and 14 days post-transplantation were used to analyze macrophage markers and interleukin (IL) levels, paracrine effects, and MSC differentiation potential by quantitative real-time polymerase chain reaction (RT-qPCR) and immunofluorescence staining. The WJ-MSCs group showed significantly higher ankle angle at 4 weeks and higher isometric tetanic force at 16 weeks, and increased expression of CD206 and IL10 at 7 or 14 days than the control group. Increased levels of neurotrophic and vascular growth factors were observed at 14 days. The WJ-MSCs group showed higher expression levels of S100β; however, the co-staining of human nuclei was faint. This study demonstrates that WJ-MSCs' immunomodulation and paracrine actions contribute to peripheral nerve regeneration more than their differentiation potential.